This is one of the most widely used workbooks. You can find digital versions and answers on platforms like GDZ.ru or Euroki.
If you are using the workbook by Gara (often paired with Kuznetsova), you can check GdzPutina. reshebnik po tetradi khimii 8 klass 2017 onlain
For those using Prosveshcheniye publications, you can use the Lecta Digital Workbook for interactive exercises. How to Find the Right One This is one of the most widely used workbooks